Investments (Payables For Collateral On Investments) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Carrying Value Of Payables For Collateral On Investments [Abstract]
Collateral payable for derivative investments	$ 2,778	$ 1,388
Securities pledged under securities lending agreements	123	114
Investments pledged for Federal Home Loan Bank of Indianapolis ('FHLBI')	4,130	3,580
Total payables for collateral on investments	7,031	5,082
Fair Value Of Related Investments Or Collateral [Abstract]
Collateral payable for derivative investments	2,778	1,388
Securities pledged under securities lending agreements	118	110
Investments pledged for Federal Home Loan Bank of Indianapolis('FHLBI')	6,718	5,480
Total payables for collateral on investments	$ 9,614	$ 6,978
Percentage of the fair value of domestic securities obtained as collateral under securities lending agreements.	102.00%
Percentage of the fair value of foreign securities obtained as collateral under securities lending agreements.	105.00%
Maximum [Member]
Fair Value Of Related Investments Or Collateral [Abstract]
Percentage of the fair value of FHLBI securities obtained as collateral under securities pledged for FHLBI for AFS Securities	115.00%
Percentage of the fair value of FHLBI securities obtained as collateral under securities pledged for FHLBI for mortgage loan	175.00%
Minimum [Member]
Fair Value Of Related Investments Or Collateral [Abstract]
Percentage of the fair value of FHLBI securities obtained as collateral under securities pledged for FHLBI for AFS Securities	105.00%
Percentage of the fair value of FHLBI securities obtained as collateral under securities pledged for FHLBI for mortgage loan	155.00%